My first impression from the title, THE VEGETATION OF ANTARCTICA THROUGH GEOLOGICAL TIME, was that this book would be mainly about paleobotanic studies in Antarctica. I found it to be much more. Both authors have carried out extensive field research in Antarctica. Although much of the discussion is centered on the evolution of vegetation through geologic time, the book also discusses global climates, paleogeography, and geology.
The book is divided into 9 chapters, each followed by several pages of cited references. The first chapter provides a concise history of exploration and summary of the geography and geology of Antarctica. The remaining 8 chapters treat the major episodes in the history of Antarctica from the mid-Paleozoic to present. Each chapter includes wide-ranging topics such as global climate change, atmospheric and oceanic conditions, plate tectonics, local geology, and evolution of plants with maps showing localities and illustrations of plant fossils. Stratigraphic charts compare flora in various southern areas. Tables include lists of species for each geologic period. Interesting case studies are included in some chapters, such as “The relictual Cenozoic flora of Antarctica and Valdivian Model.” The following chapter headings give an idea of the breadth of the topics that are covered: (1) Historical background and geological framework; (2) Early to middle Paleozoic climates and colonization of the land; (3) Collapsing ice sheets and evolving polar forests of the middle to late Paleozoic; (4) Icehouse to hothouse: floral turnover, the Permian-Triassic crisis and Triassic vegetation; (5) Gondwana break-up and landscape change across the Triassic-Jurassic transition and beyond; (6) Fern-conifer dominated Early Cretaceous (Aptian-Albian) ecosystems and the angiosperm invasion; (7) The origin of southern temperate ecosystems; (8) The heat is on: Paleogene floras and the Paleocene-Eocene warm period; and (9) After the heat: late Eocene to Pliocene climatic cooling and modification of the Antarctic vegetation.
With little to discuss in the way of Ordovician and Silurian plants and only a few reports of Devonian plants from Antarctica, the authors review the evolution of plants in general and the strong feedback between early plant history and global paleoclimates. With the evolution of vascular plants, the carbon cycle, erosion, and albedo of the Earth were changed forever. By the late Paleozoic Antarctica had drifted into a high latitudinal position where it has remained since. The supercontinent Pangea and the Panthalassan Ocean stretched from pole to pole. In Antarctica the Carboniferous terrestrial record is missing, but the authors discuss the global invasion of lower latitudes by vegetation during this time. Plants slowly invaded Antarctica as the latest Carboniferous(?)-Early Permian ice ages ended.
What struck me throughout the book is the important role that Antarctica played in our knowledge of the history of climate change. Because we live on an icehouse Earth, we tend to view climate from that perspective. Most of the time during the Phanerozoic, climates were much warmer, and extensive ice-cover was rare. Ocean currents were not driven by cold saline bottom water from a polar ice cap. The early explorers must have been amazed to find evidence of forests on a continent now so inhospitable. Antarctica was warm most of the time from about 240 million years until 34 million years ago. Trees and cold-blooded vertebrates were able to survive the darkness of polar winters throughout the Mesozoic and early Cenozoic. As the Gondwana supercontinent began to break up and Antarctica gradually became isolated from other continents, warming and cooling cycles were recorded by the poleward advance and retreat of boreal forests, some of these similar to the southern beech forests that now inhabit parts of Patagonia, Tasmania, and New Zealand. The final chapter is an excellent review of the controversy surrounding the age of the organically well preserved southern beech leaves and wood found along the Beardmore Glacier in glacial deposits that are millions of years old. A younger age (5 Ma) indicated by fossil diatoms would suggest that the East Antarctic Ice Sheet is unstable. More recent studies indicate that this flora predates the 14 Ma origin of the ice sheet.
This book is not a casual read. It would make an excellent textbook for a graduate-level university course on the geologic history of Antarctica and its place in Gondwana. I will find it useful as a reference book. It is up to date, covering the most recent hypotheses, and going deep into a broad segment of the scientific literature. The parts with which I am most familiar from my own research in the Permian and Triassic are well done. I learned much from the comprehensive discussions of the Jurassic to Paleogene geology and floras of the South Shetland Islands and Antarctic Peninsula. It is the first time that I have seen the geology and paleontology of these places reviewed so thoroughly in one publication.
